Holarctic species small to moderately large flies, 1.5-7 mm long, usually with bright red eyes when alive. Body pruinose or shiny; color varying from nearly yellow to brown or brownish-black, often with stripes or spots on thorax and a pattern of bands or spots on abdomen. Wing hyaline or with distinct darkened areas. Sexual dimorphism rare but when present, involving differences in body color or pattern, body size, wing markings, head shape, or secondary sexual traits such as armature of foreleg.